Arrays and Data Shaping

Indexed and Associative Arrays

$items = ['apple', 'banana', 'orange'];
echo $items[0];

$args = [
    'post_type'      => 'post',
    'posts_per_page' => 10,
    'post_status'    => 'publish',
];

WordPress APIs heavily use associative arrays for arguments.

Add and Read Values

$items[] = 'pear';
$settings['enabled'] = true;

$limit = isset($settings['limit']) ? absint($settings['limit']) : 10;

Merge and Defaults

$args = array_merge($defaults, $overrides);

In WordPress, use wp_parse_args() for argument defaults.

$args = wp_parse_args($args, [
    'limit' => 10,
    'order' => 'DESC',
]);

Map, Filter, Reduce

$ids = array_map('absint', $raw_ids);

$published = array_filter($posts, function ($post): bool {
    return 'publish' === $post->post_status;
});

$total = array_reduce($prices, function (float $carry, float $price): float {
    return $carry + $price;
}, 0.0);

Keys, Values, and Columns

$keys = array_keys($settings);
$values = array_values($settings);
$ids = array_column($rows, 'ID');

Strict in_array

if (in_array($layout, ['grid', 'list'], true)) {
    $safe_layout = $layout;
}

Sorting

Function	Preserves Keys	Sorts By
sort()	No	Values ascending
rsort()	No	Values descending
asort()	Yes	Values ascending
arsort()	Yes	Values descending
ksort()	Yes	Keys ascending
krsort()	Yes	Keys descending
usort()	No	Custom comparison
uasort()	Yes	Custom comparison

usort($items, function (array $a, array $b): int {
    return $a['priority'] <=> $b['priority'];
});

Destructuring and Spread

[$first, $second] = $items;
['title' => $title, 'url' => $url] = $card;

$combined = [...$default_items, ...$custom_items];

Array spread requires PHP 7.4+.

WordPress Query Arrays

$query = new WP_Query([
    'post_type'      => 'book',
    'posts_per_page' => 12,
    'tax_query'      => [
        [
            'taxonomy' => 'genre',
            'field'    => 'slug',
            'terms'    => ['fiction'],
        ],
    ],
]);

Sanitizing Arrays

$raw_ids = isset($_POST['ids']) ? (array) wp_unslash($_POST['ids']) : [];
$ids = array_map('absint', $raw_ids);
$ids = array_filter($ids);

Shape Validation

function myplugin_is_valid_card(array $card): bool {
    return isset($card['title'], $card['url'])
        && is_string($card['title'])
        && is_string($card['url']);
}

Practical WordPress Pattern

function myplugin_get_settings(): array {
    $settings = get_option('myplugin_settings', []);

    if (! is_array($settings)) {
        $settings = [];
    }

    return wp_parse_args($settings, [
        'enabled' => false,
        'limit'   => 10,
        'layout'  => 'grid',
    ]);
}

Common Pitfalls

• Assuming request arrays are shaped correctly.
• Forgetting wp_unslash() for superglobal arrays.
• Using array_merge() when numeric keys matter.
• Using in_array() without strict mode.
• Storing huge arrays in autoloaded options.
• Creating deeply nested arrays with no documented schema.